I agree that 88mm and 5" flak is stupid.
If it has to be there, it should be putting up barrages at various "probable hit" locations, rather than tracking a single fighter that is flying at 300+ MPH in a turning dogfight.
Further, the flak should not even fire when the airspace more friendlies than enemy.
When 88mm altitude bursts were fired, each shell had to be pre-set by a gun crew member. I find it HIGHLY unlikely that someone would be able to predict what altitude a figter would be at at any given moment. Let's say it took 15 seconds to fuse and set an 88mm shell... For a fighter in a dogfight, a lot can change in 15 seconds